Screw Modifier Destroying Normal in Blender
For anyone who might have the same problem. The screw modifier doesn't work well with faces. So have only edges or vertices when adding screw modifier



Here is a workaround for that problem if you really want to use the screw modifier with faces. 


step1: select your object
step2: Add screw modifier
step3: add solidify modifier
step4: play around with offset and clamp in the solidify modifier
until you get normal in the right direction.